.content {
	width: 640px;
	height: 640px;
	margin: 0 auto;
	position: relative;
}
.btn {
	width: 100%;
	height: 100%;

	position: absolute;
	left: 0;
	top: 0;
	background-color: rgba(0, 0, 0, 0.3); /* 遮罩层 */
    z-index: 2;
}
.btn button{
    background: none;
    border: none;
    background-size: 100% 100%;

    cursor: pointer;
    outline: none;

    position: absolute;
    left: 50%;
    top: 50%;
}

.startBtn button{
    width: 200px;
    height: 80px;
    background: url('../img/开始游戏.png') no-repeat center;
    margin-left: -100px;
    margin-top: -40px;
}
.pauseBtn{
    display: none;
}
.pauseBtn button{
    width: 70px;
    height: 70px;
    background: url('../img/暂停.png') no-repeat center;
    margin-left: -35px;
    margin-top: -35px;
}


/* snakeWrap */
#snakeWrap{
    width: 600px;
    height: 600px;
    background: #2ce94b;
    border: 20px solid #7dd9ff;

    position: relative;
}
/* #snakeWrap div{
    width: 20px;
    height: 20px;
} */
.snakeHead{
    background: url(../img/蛇.png);
    background-size: cover;
    /* transform: rotate(-90deg); */
}
.snakeBody{
    background: #9ddbb1;
    border-radius: 50%;
}
.food{
    background: url('../img/苹果.png');
    background-size: cover;
}